He would find it odd to see Wei Ying marry someone else, but knowing that someone else was him... it would seem like a very good play of their lives.

"If it makes you uncomfortable, Wei Ying can visit at another time. My door is open."

And if he's so concerned about other people being sad... there's no need for Wei Ying to be sad.

The music stops, but everyone seems to be having so much fun that they request another song.